Motherboard:

As we’ve reported before, it is bullshit and illegal under federal law for electronics manufacturers to put “Warranty Void if Removed” stickers on their gadgets, and it’s also illegal for companies to void your warranty if you fix your device yourself or via a third party.

And:

Companies such as Sony and Microsoft pepper the edges of their game consoles with warning labels telling customers that breaking the seal voids the warranty. That’s illegal. Thanks to the 1975 Magnuson-Moss Warranty Act, no manufacturer is allowed to put repair restrictions on a device it offers a warranty on. Dozens of companies do it anyway, and the FTC has put them on notice. Apple, meanwhile, routinely tells customers not to use third party repair companies, and aftermarket parts regularly break iPhones due to software updates.

Interesting. Going to do more reading on the Magnuson-Moss Warranty Act.